Re: [PATCH v4] hwmon: (aquacomputer_d5next) valid the data size before reading the sensor data

[Edward Adam Davis]

On Sat, 22 Aug 2026 13:55:35 +0200, Greg KH wrote:
> On Sat, Aug 22, 2026 at 07:34:35PM +0800, Edward Adam Davis wrote:
> > The user-forged sensor data is only 65 bytes long; however, aqc_raw_event()
> > fails to handle cases where the sensor data length is too small when reading
> > the data, resulting in [1] during the read process.
> 
> What is "user-forged sensor data"?
It is the data constructed within the reproducer.
> 
> > 
> > Add a data size check, if the size is less than that required for the
> > specific data item to be read, abort the sensor data read operation.
> 
> This patch does much more than that.
Got it, I will write more comments.
> 
> > 
> > [1]
> > BUG: KASAN: slab-out-of-bounds in aqc_raw_event+0x213e/0x25d0 drivers/hwmon/aquacomputer_d5next.c:1327
> > Read of size 2 at addr ffff888108aba257 by task swapper/1/0
> > Call Trace:
> >  get_unaligned_be16 include/linux/unaligned.h:48 [inline]
> >  aqc_raw_event drivers/hwmon/aquacomputer_d5next.c:1345 [inline]
> >  aqc_raw_event+0x213e/0x25d0 drivers/hwmon/aquacomputer_d5next.c:1327
> >  __hid_input_report.constprop.0+0x319/0x470 drivers/hid/hid-core.c:2168
> >  hid_irq_in+0x55d/0x710 drivers/hid/usbhid/hid-core.c:287
> >  __usb_hcd_giveback_urb+0x38d/0x610 drivers/usb/core/hcd.c:1657
> >  usb_hcd_giveback_urb+0x3ca/0x4a0 drivers/usb/core/hcd.c:1741
> > 
> > Fixes: 0e35f63f7f4e ("hwmon: add driver for Aquacomputer D5 Next")
> > Reported-by: syzbot+9ee5f5dc18673d6b2f37@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Closes: https://syzkaller.appspot.com/bug?extid=9ee5f5dc18673d6b2f37
> > Tested-by: syzbot+9ee5f5dc18673d6b2f37@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
> > ---
> 
> Was the Assisted-by: tag forgotten?
No one has assisted me so far; also, I haven't used this type of tag before.
> 
> 
> > v1 -> v2: change to check the data item and update comments
> > v2 -> v3: check all sub items and update subject
> > v3 -> v4: add speed and flow check
> > 
> >  drivers/hwmon/aquacomputer_d5next.c | 104 ++++++++++++++++++++++++++++
> >  1 file changed, 104 insertions(+)
> > 
> > diff --git a/drivers/hwmon/aquacomputer_d5next.c b/drivers/hwmon/aquacomputer_d5next.c
> > index 1ca70e726298..89c9fc0c77e5 100644
> > --- a/drivers/hwmon/aquacomputer_d5next.c
> > +++ b/drivers/hwmon/aquacomputer_d5next.c
> > @@ -1324,6 +1324,107 @@ static const struct hwmon_chip_info aqc_chip_info = {
> >  	.info = aqc_info,
> >  };
> >  
> > +/* aqc_raw_data_valid()
> > + * Does not support special-case sensor readings data size check
> 
> Why not?
It would be more appropriate for the maintainers of these sensors to add
the relevant checks.
> 
> > + */
> > +static bool aqc_raw_data_valid(struct aqc_data *priv, int size)
> > +{
> > +	int off, fan_off, i;
> > +	char *msg;
> > +
> > +	if (!priv)
> > +		return false;
> > +
> > +	/* +1 for get_unaligned_be16(), it reads 2 bytes */
> > +	off = priv->serial_number_start_offset + SERIAL_PART_OFFSET + 1;
> > +	if (off >= size) {
> > +		msg = "serial number start offset";
> 
> That's a lot of debugging code being added, why?  Who is going to use
> that?
I am not certain that these debug messages are definitely useful;
I simply included them because I felt they might be helpful.
> 
> 
> 
> > +		goto invalid;
> > +	}
> > +
> > +	off = priv->firmware_version_offset + 1;
> > +	if (off >= size) {
> > +		msg = "firmware version offset";
> > +		goto invalid;
> > +	}
> > +
> > +	/* Physical temperature sensor readings data size check*/
> > +	for (i = 0; i < priv->num_temp_sensors; i++) {
> > +		off = priv->temp_sensor_start_offset + i * AQC_SENSOR_SIZE + 1;
> > +
> > +		if (off >= size) {
> > +			msg = "temp sensor start offset";
> > +			goto invalid;
> > +		}
> > +	}
> > +
> > +	/* Virtual temperature sensor readings data size check*/
> > +	for (i = 0; i < priv->num_virtual_temp_sensors; i++) {
> > +		off = priv->virtual_temp_sensor_start_offset +
> > +		      i * AQC_SENSOR_SIZE + 1;
> > +
> > +		if (off >= size) {
> > +			msg = "virtual temp sensor start offset";
> > +			goto invalid;
> > +		}
> > +	}
> > +
> > +	/* Fan speed and related readings data size check */
> > +	if (!priv->fan_structure)
> > +		goto flow;
> > +
> > +	for (i = 0; i < priv->num_fans; i++) {
> > +		fan_off = priv->fan_sensor_offsets[i] + 1;
> > +		off = fan_off + priv->fan_structure->speed;
> > +		if (off >= size) {
> > +			msg = "fan speed offset";
> > +			goto invalid;
> > +		}
> > +
> > +		off = fan_off + priv->fan_structure->power;
> > +		if (off >= size) {
> > +			msg = "fan power offset";
> > +			goto invalid;
> > +		}
> > +
> > +		off = fan_off + priv->fan_structure->voltage;
> > +		if (off >= size) {
> > +			msg = "fan voltage offset";
> > +			goto invalid;
> > +		}
> > +
> > +		off = fan_off + priv->fan_structure->curr;
> > +		if (off >= size) {
> > +			msg = "fan curr offset";
> > +			goto invalid;
> > +		}
> > +	}
> > +
> > +flow:
> > +	/* Flow sensor readings data size check */
> > +	for (i = 0; i < priv->num_flow_sensors; i++) {
> > +		off = priv->flow_sensors_start_offset + i * AQC_SENSOR_SIZE + 1;
> > +		if (off >= size) {
> > +			msg = "flow sensors start offset";
> > +			goto invalid;
> > +		}
> > +	}
> > +
> > +	if (priv->power_cycle_count_offset != 0) {
> > +		off = priv->power_cycle_count_offset + 3;
> > +		if (off >= size) {
> > +			msg = "power cycle count offset";
> > +			goto invalid;
> > +		}
> > +	}
> > +
> > +	return true;
> > +invalid:
> > +	pr_debug("data size (%d) is less than the %s, %s\n",
> > +		 size, msg, __func__);
> 
> drivers should always use dev_dbg().
> 
> also pr_debug() already has __func__ in it.  Please fix your LLM.
Got it.

BR,
Edward